Berlin 2005 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 30: POSTER: Chemical physics

CPP 30.5: Poster

Tuesday, March 8, 2005, 16:30–18:30, Poster TU D

A modified sfa setup for single molecule tracking — •Arne Schob and Frank Cichos — Photonics and optical materials, Institute of physics, TU Chemnitz, 09107 Chemnitz

A surface forces apparatus (sfa) is a well established technique to study liquid-substrate interactions in ultrathin confined films on mesoscopic lengthscales. Shear experiments whithin a sfa can help understanding friction with ultrathin lubricant layers more detailed allthough a conventional sfa is limited to ensemble measurements. Tracking of single molecules could be of tremendous benefit here, because anisotropies and inhomogeneities in the molecular diffusion can easily be revealed.

For the first time we present a surface forces apparatus, which has been modified to provide access to molecular motion within confined liquids using single fluorescent molecule tracking. Force-distance-curves of our setup demonstrate that a capacitive position sensor is able to replace the common interferometrical thickness measurement. With a separation of external force driven motion (shear) from stochastic driven diffusion we demonstrate the possibility to investigate molecular details of confined liquids under shear, which may serve as a model for ultrathin lubricant layers between solid surfaces.